Reducing frequent handoffs of a wireless communication device

ABSTRACT

A method for reducing frequent idle handoffs of a wireless communication device is described. A registration request is received by a base station or a femto access point from the wireless communication device. The number of registration requests received from the wireless communication device are counted while the registration timer is running. It is determined that frequent handoffs are happening when the number of registration requests received is greater than a registration threshold. A transmit power of a femto access point is adjusted if the number of registration requests received indicates that frequent handoffs are happening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and claims priority to, U.S. patentapplication Ser. No. 12/789,213, filed May 27, 2010, for “ReducingFrequent Handoffs of a Wireless Communication Device,” which claims thebenefit of priority to U.S. Provisional Patent Application Ser. No.61/181,882, filed May 28, 2009, for “Optimization of Idle Mode Searchand Handoffs in Femto-Macro Deployments,” of which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems. More specifically, the present disclosure relates to systemsand methods for reducing frequent handoffs of a wireless communicationdevice to/from a femto access point.

BACKGROUND

Wireless communication systems have become an important means by whichmany people worldwide have come to communicate. A wireless communicationsystem may provide communication for a number of mobile stations, eachof which may be serviced by a base station.

It may be beneficial to use localized base stations that provide serviceto a select group of mobile stations. These localized base stations mayuse less power and have smaller coverage areas than normal basestations. The localized base stations may then provide a mobile stationwith active voice/data access. As localized base stations continue toimprove, more localized base stations will become prevalent.

Examples of localized base stations include femtocells and picocells.Localized base stations may be referred to as femto access pointswithout loss of generality. These localized base stations may becontrolled by a user. For example, a localized base station may bepurchased by an end user and placed in their home or office to increasewireless coverage. A localized base station may also be controlled by aservice provider. For example, a service provider may place a localizedbase station in a public area with high traffic.

As a mobile station approaches a localized base station, the mobilestation may detect the localized base station and attempt to access itby sending a registration request. The localized base station may thendetermine whether to allow access to this mobile station for differentservices such as a voice/data connection with the mobile station.Registration requests reduce the battery life of the mobile station andincrease the network load. As such, benefits may be realized by reducingthe number of registration requests made by a mobile station.

SUMMARY

A method for reducing frequent idle handoffs of a wireless communicationdevice is described. A registration request is received from thewireless communication device. A registration timer is started. A numberof registration requests received from the wireless communication deviceis counted while the registration timer is running It is determinedwhether the number of registration requests received is greater than aregistration threshold. A transmit power of a femto access point isadjusted if the number of registration requests received is greater thanthe registration threshold.

The wireless communication device may be part of a closed subscribergroup (CSG) associated with the femto access point. Adjusting thetransmit power of the femto access point may include increasing thetransmit power of the femto access point. The wireless communicationdevice may not be part of a closed subscriber group (CSG) associatedwith the femto access point. Adjusting the transmit power of the femtoaccess point may include decreasing the transmit power of the femtoaccess point. The transmit power of the femto access point may beadjusted by a power adjustment factor.

A power adjustment timer with a power adjustment time may be started. Itmay be determined whether the power adjustment timer has expired. Italso may be determined whether frequent idle handoffs by the wirelesscommunication device were detected while the power adjustment timer wasrunning Frequent handoffs by the wireless communication device may bedetected while the power adjustment timer was running. The poweradjustment time may be incrementally increased. The power adjustmentfactor may also be incrementally increased.

Frequent handoffs by the wireless communication device may not bedetected while the power adjustment timer was running. The poweradjustment time may be incrementally decreased. The power adjustmentfactor may also be incrementally decreased. The transmit power may bereadjusted to a previous transmit power. Adjusting the transmit power ofthe femto access point may include adjusting a total forward linktransmit power of the femto access point or adjusting a forward linkpilot transmit power of the femto access point. A registration requestmay be an active handoff request passed via a core network.

A wireless device configured for reducing frequent idle handoffs of awireless communication device is also described. The wireless deviceincludes a processor, memory in electronic communication with theprocessor and instructions stored in the memory. The instructions areexecutable by the processor to receive a registration request from thewireless communication device. The instructions are also executable bythe processor to start a registration timer. The instructions arefurther executable by the processor to count a number of registrationrequests received from the wireless communication device while theregistration timer is running. The instructions are also executable bythe processor to determine whether the number of registration requestsreceived is greater than a registration threshold. The instructions arefurther executable by the processor to adjust a transmit power of thewireless device if the number of registration requests received isgreater than the registration threshold.

A method for reducing frequent idle handoffs of a wireless communicationdevice is described. A registration request is sent to a femto accesspoint. A trigger for an idle handoff away from the femto access point isdetected. A handout timer is started. It is determined whether a handouttrigger condition is satisfied within a monitoring period after thehandout timer has expired.

The trigger for an idle handoff away from the femto access point may bean idle handout trigger. An idle handoff away from the femto accesspoint may be performed if the handout trigger condition is satisfiedwithin a monitoring period after the handout timer has expired. Themethod may include staying on the femto access point if the handouttrigger condition is not satisfied within a monitoring period after thehandout timer has expired.

A forward link received power from the femto access point may becompared with a handout threshold before the handout timer has expired.The idle handoff away from the femto access point may be performed priorto the handout timer expiring if the forward link received power fromthe femto access point is less than the handout threshold.

An observation timer may be started. A number of registrations attemptedto the femto access point before the observation timer has expired maybe counted. An idle handoff away from the femto access point may beperformed after the observation timer has expired if the number ofregistrations attempted to the femto access point is greater than anobservation threshold and handoff away from the femto access point istriggered.

The wireless communication device may be part of a closed subscribergroup (CSG) associated with the femto access point. The wirelesscommunication device may also not be part of a closed subscriber group(CSG) associated with the femto access point. The trigger for an idlehandoff away from the femto access point may be to a macro base station.The wireless communication device may be able to distinguish betweenpilots received from the femto access point and pilots received from amacro base station.

A wireless device configured for reducing frequent idle handoffs of thewireless device is also described. The wireless device includes aprocessor, memory in electronic communication with the processor andinstructions stored in the memory. The instructions are executable bythe processor to send a registration request to a femto access point.The instructions are also executable by the processor to detect atrigger for an idle handoff away from the femto access point. Theinstructions are further executable by the processor to start a handouttimer. The instructions are also executable by the processor todetermine whether a handout trigger condition is satisfied within amonitoring period after the handout timer has expired.

A method for reducing frequent idle handoffs of a wireless communicationdevice is described. The method includes determining that changes to anidle mode pilot search trigger threshold are needed. The idle mode pilotsearch trigger threshold is adjusted.

The method may be performed by a femto access point. Adjusting the idlemode pilot search trigger threshold may include sending instructions tothe wireless communication device to adjust the idle mode pilot searchtrigger threshold.

The method may be performed by the wireless communication device.Determining that changes to an idle mode pilot search trigger thresholdare needed may include receiving instructions to adjust the idle modepilot search trigger threshold from a femto access point.

A wireless device configured for reducing frequent idle handoffs of awireless communication device is also described. The wireless deviceincludes a processor, memory in electronic communication with theprocessor and instructions stored in the memory. The instructions areexecutable by the processor to determine that changes to an idle modepilot search trigger threshold are needed. The instructions are alsoexecutable by the processor to adjust the idle mode pilot search triggerthreshold.

A wireless device configured for reducing frequent idle handoffs of awireless communication device is described. The wireless device includesmeans for receiving a registration request from the wirelesscommunication device. The wireless device also includes means forstarting a registration timer. The wireless device further includesmeans for counting a number of registration requests received from thewireless communication device while the registration timer is runningThe wireless device also includes means for determining whether thenumber of registration requests received is greater than a registrationthreshold. The wireless device further includes means for adjusting atransmit power of the femto access point if the number of registrationrequests received is greater than the registration threshold.

A computer-program product for reducing frequent idle handoffs of awireless communication device is described. The computer-program productincludes a computer-readable medium having instructions thereon. Theinstructions include code for causing at least one computer to receive aregistration request from the wireless communication device. Theinstructions also include code for causing at least one computer tostart a registration timer. The instructions further include code forcausing at least one computer to count a number of registration requestsreceived from the wireless communication device while the registrationtimer is running The instructions also include code for causing at leastone computer to determine whether the number of registration requestsreceived is greater than a registration threshold. The instructionsfurther include code for causing at least one computer to adjust atransmit power of the femto access point if the number of registrationrequests received is greater than the registration threshold.

A wireless device configured for reducing frequent idle handoffs of thewireless device is also described. The wireless device includes meansfor sending a registration request to a femto access point. The wirelessdevice also includes means for detecting a trigger for an idle handoffaway from the femto access point. The wireless device further includesmeans for starting a handout timer. The wireless device also includesmeans for determining whether a handout trigger condition is satisfiedwithin a monitoring period after the handout timer has expired.

A computer-program product for reducing frequent idle handoffs of awireless communication device is described. The computer-program productis a computer-readable medium having instructions thereon. Theinstructions include code for causing at least one computer to send aregistration request to a femto access point. The instructions alsoinclude code for causing at least one computer to detect a trigger foran idle handoff away from the femto access point. The instructionsfurther include code for causing at least one computer to start ahandout timer. The instructions also include code for determiningwhether a handout trigger condition is satisfied within a monitoringperiod after the handout timer has expired.

A wireless device configured for reducing frequent idle handoffs of awireless communication device is described. The wireless device includesmeans for determining that changes to an idle mode pilot search triggerthreshold are needed. The wireless device also includes means foradjusting the idle mode pilot search trigger threshold.

A computer-program product for reducing frequent idle handoffs of awireless communication device is described. The computer-program productis a computer-readable medium having instructions thereon. Theinstructions include code for causing at least one computer to determinethat changes to an idle mode pilot search trigger threshold are needed.The instructions also include code for causing at least one computer toadjust the idle mode pilot search trigger threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system, configured tosupport a number of users, in which the teachings herein may beimplemented;

FIG. 2 illustrates an exemplary communication system where one or morefemto nodes are deployed within a network environment;

FIG. 3 illustrates an example of a coverage map where several trackingareas (or routing areas or location areas) are defined, each of whichincludes several macro coverage areas;

FIG. 4 shows a wireless communication system with multiple wirelessdevices;

FIG. 5 is a block diagram of a frequent handoff reduction module;

FIG. 6 is a flow diagram of a method for reducing frequent handoffs;

FIG. 7 illustrates means-plus-function blocks corresponding to themethod of FIG. 6;

FIG. 8 is another flow diagram of a method for reducing frequenthandoffs;

FIG. 9 illustrates means-plus-function blocks corresponding to themethod of FIG. 8;

FIG. 10 is a flow diagram of yet another method for reducing frequenthandoffs;

FIG. 11 illustrates means-plus-function blocks corresponding to themethod of FIG. 10;

FIG. 12 is a block diagram illustrating a handoff determination module;

FIG. 13 is a flow diagram of a method for reducing handoffs by awireless communication device;

FIG. 14 illustrates means-plus-function blocks corresponding to themethod of FIG. 13;

FIG. 15 is a flow diagram of another method for reducing frequenthandoffs by a wireless communication device;

FIG. 16 illustrates means-plus-function blocks corresponding to themethod of FIG. 15;

FIG. 17 illustrates two wireless devices in a multiple-in andmultiple-out (MIMO) system;

FIG. 18 illustrates certain components that may be included within afemto access point; and

FIG. 19 illustrates certain components that may be included within awireless communication device.

DETAILED DESCRIPTION

FIG. 1 illustrates a wireless communication system 100, configured tosupport a number of users, in which the teachings herein may beimplemented. The system 100 provides communication for multiple cells102, such as, for example, macro cells 102A-102G, with each cell beingserviced by a corresponding access node 104 (e.g., access nodes104A-104G). As shown in FIG. 1, access terminals 106 (e.g., accessterminals 106A-106L) may be dispersed at various locations throughoutthe system over time. Each access terminal 106 may communicate with oneor more access nodes 104 on a forward link (“FL”) and/or a reverse link(“RL”) at a given moment, depending upon whether the access terminal 106is active and whether it is in soft handoff, for example. The wirelesscommunication system 100 may provide service over a large geographicregion. For example, macro cells 102A-102G may cover a few blocks in aneighborhood.

In some aspects, the teachings herein may be employed in a network thatincludes macro scale coverage (e.g., a large area cellular network suchas a 3G networks, typically referred to as a macro cell network) andsmaller scale coverage (e.g., a residence-based or building-basednetwork environment). As an access terminal (“AT”) moves through such anetwork, the access terminal may be served in certain locations byaccess nodes (“ANs”) that provide macro coverage while the accessterminal may be served at other locations by access nodes that providesmaller scale coverage. In some aspects, the smaller coverage nodes maybe used to provide incremental capacity growth, in-building coverage anddifferent services (e.g., for a more robust user experience). In thediscussion herein, a node that provides coverage over a relatively largearea may be referred to as a macro node. A node that provides coverageover a relatively small area (e.g., a residence) may be referred to as afemto node. A node that provides coverage over an area that is smallerthan a macro area and larger than a femto area may be referred to as apico node (e.g., providing coverage within a commercial building).

A cell associated with a macro node, a femto node or a pico node may bereferred to as a macro cell, a femto cell, or a pico cell, respectively.In some implementations, each cell may be further associated with (e.g.,divided into) one or more sectors.

In various applications, other terminology may be used to reference amacro node, a femto node, or a pico node. For example, a macro node maybe configured or referred to as an access node, base station, macro basestation, access point, evolved NodeB (eNB), macro cell and so on. Also,a femto node may be configured or referred to as a Home NodeB (HNB),Home evolved NodeB (HeNB), access point base station, femto cell, femtoaccess point and so on.

FIG. 2 illustrates an exemplary communication system 200 where one ormore femto nodes, also known as femto access points, are deployed withina network environment. The system 200 includes multiple femto nodes 211(e.g., femto nodes 211A and 211B) installed in a relatively small scalenetwork environment (e.g., in one or more user residences 208). Eachfemto node 211 may be coupled to a wide area network 214 (e.g., theInternet) and a mobile operator core network 212 via a DSL router, acable modem, a wireless link or other connectivity means (not shown). Aswill be discussed below, each femto node 211 may be configured to serveassociated access terminals 206, also known as user equipment, (e.g.,access terminal 206A) and, optionally, alien access terminals 206 (e.g.,access terminal 206B). In other words, access to femto nodes 211 may berestricted whereby a given femto node 211 may serve a set of designatedaccess terminals 206 (e.g., home access terminals 206) but may serve anynon-designated access terminals 206 (e.g., access terminals 206 of aneighbor).

The owner of a femto node 211 may subscribe to mobile service, such as,for example, 3G mobile service, offered through the mobile operator corenetwork 212. In addition, an access terminal 206 may be capable ofoperating both in macro environments and in smaller scale (e.g.,residential) network environments. In other words, depending on thecurrent location of the access terminal 206, the access terminal 206 maybe served by an access node 210 of the macro cell mobile network or byany one of a set of femto nodes 211 (e.g., the femto nodes 211A and 211Bthat reside within a corresponding user residence 208). For example,when a subscriber is outside his home, he is served by a standard macroaccess node (e.g., node 210) and when the subscriber is at home, he isserved by a femto node (e.g., node 211A). Here, it should be appreciatedthat a femto node 211 may be backward compatible with existing accessterminals 206.

A femto node 211 may be deployed on a single frequency or, in thealternative, on multiple frequencies. Depending on the particularconfiguration, the single frequency or one or more of the multiplefrequencies may overlap with one or more frequencies used by a macronode (e.g., node 210).

In some aspects, an access terminal 206 may be configured to connect toa preferred femto node (e.g., the home femto node of the access terminal206) whenever such connectivity is possible. For example, whenever theaccess terminal 206 is within the user's residence 208, it may bedesired that the access terminal 206 communicate only with the homefemto node 211.

In some aspects, if the access terminal 206 operates within the macrocellular network 210 but is not residing on its most preferred network(e.g., as defined in a preferred roaming list), the access terminal 206may continue to search for the most preferred network (e.g., thepreferred femto node 211) using a Better System Reselection (“BSR”),which may involve a periodic scanning of available systems to determinewhether better systems are currently available, and subsequent effortsto associate with such preferred systems. The access terminal 206 maylimit the search for specific band and channel. For example, the searchfor the most preferred system may be repeated periodically. Upondiscovery of a preferred femto node 211, the access terminal 206 selectsthe femto node 211 for camping within its coverage area.

A femto node may be restricted in some aspects. For example, a givenfemto node may only provide certain services to certain accessterminals. In deployments with so-called restricted (or closed)association, a given access terminal may only be served by the macrocell mobile network and a defined set of femto nodes (e.g., the femtonodes 211 that reside within the corresponding user residence 208). Insome implementations, a node may be restricted to not provide signaling,data access, registration, paging or service.

In some aspects, a restricted femto node (which may also be referred toas a Closed Subscriber Group Home NodeB) is one that provides service toa restricted provisioned set of access terminals. This set may betemporarily or permanently extended as necessary. In some aspects, aClosed Subscriber Group (“CSG”) may be defined as the set of accessterminals/subscribers to which access to the restricted femto node isallowed. A channel on which all femto nodes (or all restricted femtonodes) in a region operate may be referred to as a femto channel.

Various relationships may thus exist between a given femto node and agiven access terminal. For example, from the perspective of an accessterminal, an open femto node may refer to a femto node with norestricted association. A restricted femto node may refer to a femtonode that is restricted in some manner (e.g., restricted for associationand/or registration). A home femto node may refer to a femto node onwhich the access terminal is authorized to access and operate on. Aguest femto node may refer to a femto node on which an access terminalis temporarily authorized to access or operate on. An alien femto nodemay refer to a femto node on which the access terminal is not authorizedto access or operate on, except for perhaps emergency situations (e.g.,911 calls).

From a restricted femto node perspective, a home access terminal mayrefer to an access terminal that is authorized to access the restrictedfemto node. A guest access terminal may refer to an access terminal withtemporary access to the restricted femto node. An alien access terminalmay refer to an access terminal that does not have permission to accessthe restricted femto node, except for perhaps emergency situations, forexample, such as 911 calls (e.g., an access terminal that does not havethe credentials or permission to register with the restricted femtonode).

For convenience, the disclosure herein describes various functionalityin the context of a femto node. It should be appreciated, however, thata pico node may provide the same or similar functionality for a largercoverage area. For example, a pico node may be restricted, a home piconode may be defined for a given access terminal, and so on.

FIG. 3 illustrates an example of a coverage map 300 where severaltracking areas 315 (or routing areas or location areas) are defined,each of which includes several macro coverage areas 316. Here, areas ofcoverage associated with tracking areas 315A, 315B and 315C aredelineated by the wide lines and the macro coverage areas 316A and 316Bare represented by the hexagons. The tracking areas 315 also includefemto coverage areas 317A, 317B and 317C. In this example, each of thefemto coverage areas 317 (e.g., femto coverage area 317C) is depictedwithin a macro coverage area 316 (e.g., macro coverage area 316B). Itshould be appreciated, however, that a femto coverage area 317 may notlie entirely within a macro coverage area 316. In practice, a largenumber of femto coverage areas 317 may be defined with a given trackingarea 315 or macro coverage area 316. Also, one or more pico coverageareas (not shown) may be defined within a given tracking area 315 ormacro coverage area 316.

FIG. 4 shows a wireless communication system 400 with multiple wirelessdevices. Wireless communication systems 400 are widely deployed toprovide various types of communication content such as voice, data, andso on. These systems may be multiple-access systems capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., bandwidth and transmit power). A wireless devicemay be a base station or a wireless communication device.

A base station is a station that communicates with one or more wirelesscommunication devices. A base station may also be referred to as, andmay include some or all of the functionality of, an access point, abroadcast transmitter, a NodeB, an evolved NodeB, etc. The term “basestation” will be used herein. Each base station provides communicationcoverage for a particular geographic area. A base station may providecommunication coverage for one or more wireless communication devices.The term “cell” can refer to a base station and/or its coverage areadepending on the context in which the term is used.

A mobile station or device may be referred to as a wirelesscommunication device. A base station may be referred to as an evolvedNodeB (eNB). A semi-autonomous base station may be referred to as a homeevolved NodeB (HeNB). An HeNB may thus be one example of an eNB. TheHeNB and/or the coverage area of an HeNB may be referred to as afemtocell, a picocell, a home NodeB (HNB) cell, an HeNB cell, a femtoaccess point, a femto node or a closed subscriber group (CSG) cell.Femto access point terminology is used hereinafter. Femto access pointsare low power base stations that extend the range of conventional widearea network base stations. Femto access points provide voice and highspeed data service inside homes and offices for wireless communicationdevices supporting cellular radio communication techniques. Access to afemto access point depends on the kind of access control that the femtoaccess point uses. With open access, any wireless communication devicecan access and receive service from a femto access point. With closedsubscriber group (CSG) or restricted access, only members of the closedsubscriber group (CSG) are allowed to access and receive service from afemto access point 419.

Communications in a wireless system (e.g., a multiple-access system) maybe achieved through transmissions over a wireless link. Such acommunication link may be established via a single-input andsingle-output (SISO), multiple-input and single-output (MISO), or amultiple-input and multiple-output (MIMO) system. A MIMO system includestransmitter(s) and receiver(s) equipped, respectively, with multiple(NT) transmit antennas and multiple (NR) receive antennas for datatransmission. SISO and MISO systems are particular instances of a MIMOsystem. The MIMO system can provide improved performance (e.g., higherthroughput, greater capacity or improved reliability) if the additionaldimensionalities created by the multiple transmit and receive antennasare utilized.

A MIMO system may support time division duplex (TDD) and frequencydivision duplex (FDD). In a TDD system, the uplink and downlinktransmissions are on the same frequency region so that the reciprocityprinciple allows the estimation of the uplink channel from the downlinkchannel.

The teachings herein may be incorporated into various types ofcommunication systems and/or system components. In some aspects, theteachings herein may be employed in a multiple-access system capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., by specifying one or more of bandwidth, transmitpower, coding, interleaving, and so on). For example, the teachingsherein may be applied to any one or combinations of the followingtechnologies: Code Division Multiple Access (CDMA) systems,Multiple-Carrier CDMA (MCCDMA), Wideband CDMA (W-CDMA), High-SpeedPacket Access (HSPA, HSPA+) systems, Time Division Multiple Access(TDMA) systems, Frequency Division Multiple Access (FDMA) systems,Single-Carrier FDMA (SC-FDMA) systems, Orthogonal Frequency DivisionMultiple Access (OFDMA) systems or other multiple access techniques.

A wireless communication system employing the teachings herein may bedesigned to implement one or more standards, such as IS-95, cdma2000,IS-856, W-CDMA, time division synchronous code division multiple access(TD-SCDMA) and other standards. A CDMA network may implement a radiotechnology such as Universal Terrestrial Radio Access (UTRA), cdma2000or some other technology. UTRA includes W-CDMA and Low Chip Rate (LCR).The cdma2000 technology covers IS-2000, IS-95 and IS-856 standards. ATDMA network may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology such as Evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE802.20, Flash-OFDM®, etc. UTRA, E-UTRA and GSM are part of UniversalMobile Telecommunication System (UMTS). The teachings herein may beimplemented in a Third Generation Partnership Project (3GPP) Long TermEvolution (LTE) system, an Ultra-Mobile Broadband (UMB) system and othertypes of systems. LTE is a release of UMTS that uses E-UTRA. Althoughcertain aspects of the disclosure may be described using 3GPPterminology, it is to be understood that the teachings herein may beapplied to 3GPP (Rel99, Rel5, Rel6, Rel7) technology, as well as 3GPP2(IxRTT, 1xEV-DO RelO, RevA, RevB) technology and other technologies. Forclarity, certain aspects of the techniques are described below forcdma2000, and cdma2000 terminology is used in much of the descriptionbelow.

Low power base stations such as home NodeBs (HNBs), home evolved NodeBs(HeNB), picocells and femtocells are used in addition to the normal basestations (a normal base station is referred to herein as a macro basestation 418). A picocell may refer to a base station controlled by thenetwork operator that operates on a much smaller scale than a macro basestation. A femtocell may refer to a base station controlled by aconsumer that operates on a much smaller scale than a macro basestation. A femtocell may provide service to a closed subscriber group(CSG). HNBs, HeNBs, picocells and femtocells are referred to herein asfemto access points 419.

A femto access point 419 may provide benefits to a subscriber in theform of improved coverage inside the house/office and the possibility ofspecial pricing plans. For example, an operator may provide unlimitedvoice/data usage when the user is using a femto access point 419 for anominal charge. The operator may benefit from additional system capacitymade available by offloading some of the traffic to femto access points419.

From both a user and an operator perspective, it is desirable tomaximize usage of a femto access point. When a user comes home, awireless communication device 420 should perform idle handoff from amacro base station 418 to the femto access point 419 so that the usercan initiate/receive calls using the femto access point 419. Whilemoving around the home, the wireless communication device 420 may stayin idle mode (camp) on the femto access point 419 as long as thecoverage of the femto access point 419 is adequate. A good mechanism isneeded to control idle handoff by a wireless communication device 420,make a wireless communication device 420 stay connected to a femtoaccess point 419 in idle mode and/or active mode longer (i.e. “stick tothe femto access point 419”) and prevent frequent idle handoffs betweena femto access point 419 and a macro base station 418 in cdma2000systems.

A base station may communicate with one or more wireless communicationdevices 420 a-b. A wireless communication device 420 may also bereferred to as, and may include some or all of the functionality of, aterminal, an access terminal, a user equipment (UE), a subscriber unit,a station, etc. A wireless communication device 420 may be a cellularphone, a personal digital assistant (PDA), a wireless device, a wirelessmodem, a handheld device, a laptop computer, etc. A wirelesscommunication device 420 may communicate with zero, one or multiple basestations on the forward link 423 a-d and/or reverse link 424 a-d at anygiven moment. The forward link 423 (or downlink) refers to thecommunication link from a base station to a wireless communicationdevice 420 and the reverse link 424 (or uplink) refers to thecommunication link from a wireless communication device 420 to a basestation.

A first wireless communication device 420 a may be part of a closedsubscriber group (CSG) associated with the femto access point 419. Thefemto access point 419 may allow access only to wireless communicationdevices 420 that are part of the closed subscriber group (CSG). Withsignaling only access, wireless communication devices 420 that are notpart of a closed subscriber group (CSG) are allowed to exchangesignaling messages with the core network using the femto access point419. However, in signaling only access, the wireless communicationdevices 420 that are not part of the closed subscriber group (CSG) arenot allowed active mode voice/data service from the femto access point419.

The first wireless communication device 420 a may switch betweencommunicating with a macro base station 418 and communicating with thefemto access point 419. Because the first wireless communication device420 a is part of the closed subscriber group (CSG) associated with thefemto access point 419, it may be desirable for the first wirelesscommunication device 420 a to communicate with the femto access point419 as long as coverage by the femto access point 419 is adequate. Thisway, the femto access point 419 usage may be maximized. When the firstwireless communication device 420 a enters the coverage area of thefemto access point 419, the first wireless communication device 420 amay perform an idle handoff from the macro base station 418 to the femtoaccess point 419 so that the first wireless communication device 420 acan initiate/receive calls using the femto access point 419. An idlehandoff refers to a handoff from one base station to another when awireless communication device 420 is not in an active call.

When the coverage of the femto access point 419 is not adequate for thefirst wireless communication device 420 a, the first wirelesscommunication device 420 a may perform an idle handoff from the femtoaccess point 419 to the macro base station 418. Typically, a wirelesscommunication device 420 such as a cdma2000 1x mobile will wake upperiodically to scan forward link 423 pilot signals from other basestations. If the forward link 423 pilot signal strength from anotherbase station is greater than the forward link 423 pilot signal strengthof the current serving base station by a certain threshold (usinghysteresis), which is typically around 3 decibels (dB), then thewireless communication device 420 will perform an idle handoff to theother base station.

A deep channel fade on the forward link 423 of the femto access point419 to the first wireless communication device 420 a may trigger theidle handoff. If the forward link 423 c signal strength of the femtoaccess point 419 and the forward link 423 a signal strength of the macrobase station 418 have similar average values, the first wirelesscommunication device 420 a may handoff back and forth between the femtoaccess point 419 and the macro base station 418. These frequent idlehandoffs can drain the battery of the first wireless communicationdevice 420 a. Frequent idle handoffs can also increase the networksignaling load, because the wireless communication device 420 performs aregistration with the network each time the wireless communicationdevice 420 performs an idle handoff. To avoid frequent idle handoffsbetween the femto access point 419 and the macro base station 418, thefirst wireless communication device 420 a may use a handoffdetermination module 421 a. The handoff determination module 421 a isdiscussed in further detail below in relation to FIG. 12.

The second wireless communication device 420 b may not be part of theclosed subscriber group (CSG) associated with the femto access point419. However, the second wireless communication device 420 b may belocated nearby the femto access point 419. The second wirelesscommunication device 420 b may receive communications from the macrobase station 418 via a forward link 423 b and send communications to themacro base station 418 via a reverse link 424 b.

Like the first wireless communication device 420 a, the second wirelesscommunication device 420 b may periodically wake-up to scan pilots fromother base stations (i.e., to measure the forward link 423 d pilotsignal strength from the femto access point 419 to the second wirelesscommunication device 420 b). If the forward link 423 d pilot signalstrength from the femto access point 419 is greater than the forwardlink 423 b pilot signal strength received from the macro base station418, the second wireless communication device 420 b may attempt an idlehandoff from the macro base station 418 to the femto access point 419.Even though this idle handoff may be denied (because the second wirelesscommunication device 420 b is not part of the closed subscriber group(CSG) associated with the femto access point 419), an idle handoffattempt may still burden network resources. To avoid frequent idlehandoff attempts between the macro base station 418 and the femto accesspoint 419, the second wireless communication device 420 b may use ahandoff determination module 421 b. The handoff determination module 421b is discussed in further detail below in relation to FIG. 12.

The femto access point 419 may attempt to prevent frequent idle handoffsfrom wireless communication devices 420 that are part of the closedsubscriber group (CSG) associated with the femto access point 419 (i.e.,the first wireless communication device 420 a) and wirelesscommunication devices 420 that are not part of the closed subscribergroup (CSG) associated with the femto access point 419 (i.e., the secondwireless communication device 420 b) using a frequent handoff reductionmodule 422. The frequent handoff reduction module 422 is discussed infurther detail below in relation to FIG. 5.

Upon detecting frequent handoffs by the first wireless communicationdevice 420 a, the frequent handoff reduction module 422 may increase thetransmit power of the femto access point 419 to increase the coveragearea of the femto access point 419 and bring the first wirelesscommunication device 420 a out of the frequent handoff cycle. Upondetecting frequent handoffs by the second wireless communication device420 b, the frequent handoff reduction module 422 may reduce the transmitpower of the femto access point 419 to decrease the coverage area of thefemto access point 419 and bring the second wireless communicationdevice 420 b out of the frequent handoff cycle.

FIG. 5 is a block diagram of a frequent handoff reduction module 522.The frequent handoff reduction module 522 of FIG. 5 is one configurationof the frequent handoff reduction module 422 of FIG. 4. The frequenthandoff reduction module 522 may be on a femto access point 419. Thefrequent handoff reduction module 522 may include a registrationattempts counter 525. The registration attempts counter 525 may countthe number 526 of registration attempts made by one or more wirelesscommunication devices over a certain time period (e.g., N hours or Ndays).

In idle mode (no active, ongoing voice/data session), a wirelesscommunication device 420 (such as a cdma2000 mobile station) will turnoff all its circuitry and enter a sleep state most of the time toconserve battery life. The wireless communication device 420 wakes upperiodically to monitor any incoming pages from the network. When thewireless communication device 420 wakes up, it performs intra-frequencyand inter-frequency searches to find neighboring base stations using alist (e.g., a Neighbor List Message) provided by the current servingbase station.

Neighboring base stations on the same frequency as the current servingbase station are searched more often. Different frequencies are searchedonly when the forward link 423 power ratio Ecp/Io from the currentserving base station falls below a certain threshold (Ecp=received pilotsignal power from a particular base station, Io=total received signalpower including noise). An idle handoff registration attempt isperformed if the forward link 423 power ratio Ecp/Io from a non-servingbase station is better than the forward link 423 power ratio Ecp/Io fromthe current serving base station point by some hysteresis margin.Additional criteria may be followed by the wireless communication device420 to perform handoff.

Every idle handoff registration attempt may not be successful. Forexample, the non-serving base station may use access constraints thatprevent certain wireless communication devices 420 (that are not part ofthe closed subscriber group (CSG) associated with the non-serving basestation) from performing an idle handoff to the non-serving basestation. The wireless communication device 420 may attempt an idlehandoff registration but be denied by the non-serving base station. Idlehandoff registration attempts that are denied are still counted by theregistration attempts counter 525.

The frequent handoff reduction module 522 may also include aregistration threshold 527. The registration threshold 527 may be apredefined threshold that limits the number 526 of registration attemptsmade by a wireless communication device 420 before the femto accesspoint 419 takes action to reduce the frequent handoffs. The frequenthandoff reduction module 522 may include a different registrationthreshold 527 for wireless communication devices 420 that are part ofthe closed subscriber group (CSG) associated with the femto access point419 than for wireless communication devices 420 that are not part of theclosed subscriber group (CSG).

The frequent handoff reduction module 522 may also include aregistration timer 528 with a registration time 529. The frequenthandoff reduction module 411 may count the number 526 of registrationattempts made by a wireless communication device 420 while theregistration timer 528 is running and compare the number 526 ofregistration attempts with the registration threshold 527. The frequenthandoff reduction module 522 may then increase/decrease a transmit power535 of the femto access point 419 if the number of registration attemptsis greater than the registration threshold 527. Whenincreasing/decreasing the transmit power 535, changes may be made to thetotal forward link transmit power (Ior_tx) 536 or to the forward linkpilot transmit power (Ecp_tx) 537. Changes made to the total forwardlink transmit power (Ior_tx) 536 may also change the forward link pilottransmit power (Ecp_tx) 537 because the pilot power gain is relative tothe total transmit power. As an example, in current macro base stations418, the forward link pilot transmit power 537 is ˜20% and the overheadchannel power is ˜15% of the total available transmit power. Theremaining power is reserved to serve a large number of users under themacro base station 418 coverage. However, the number of users that afemto access point 419 is likely to serve is very limited (around fouror five). Therefore, a larger fraction of power can be allocated topilot and overhead channels.

The frequent handoff reduction module 522 may include a power adjustmentfactor 532 and a power adjustment timer 533 with a power adjustment time534. The power adjustment factor 532 may be a configurable factor thatadjusts the transmit power 535 of the femto access point 419 up or down(e.g., 2 dB up or 2 dB down). The power adjustment factor 532 may adjustthe total forward link transmit power 536 or the forward link pilottransmit power 537. Power adjustment factors 532 and the poweradjustment timer 533 are discussed in additional detail below inrelation to FIG. 10.

FIG. 6 is a flow diagram of a method 600 for reducing frequent handoffs.The method 600 may be performed by a femto access point 419. The femtoaccess point 419 may receive 602 a registration request from a wirelesscommunication device 420. The wireless communication device 420 may ormay not belong to a closed subscriber group (CSG) associated with thefemto access point 419. The wireless communication device 420 mayperform an idle handoff from a macro base station 418 to the femtoaccess point 419 by first sending a registration request to the femtoaccess point 419. Upon receiving 602 the registration request, the femtoaccess point 419 may start 604 a registration timer 528.

The femto access point 419 may count 606 the number 526 of registrationrequests received from the wireless communication device 420 during theregistration time 529. Once the registration timer 528 has expired 608,the femto access point 419 may then determine 610 whether the number 526of registration requests received from the wireless communication device420 is greater than a registration threshold 527. If the number 526 ofregistration requests received from the wireless communication device420 is not greater than the registration threshold 527, the femto accesspoint 419 may wait to receive 602 another registration request from awireless communication device 420.

If the number 527 of registration requests received from the wirelesscommunication device 420 is greater than the registration threshold 527,the femto access point 419 may adjust 612 the transmit power 535 of thefemto access point 419 accordingly. In one configuration, adjusting 612the transmit power 535 may include adjusting the total forward linktransmit power (Ior_tx) 536, which also adjusts the forward link pilottransmit power (Ecp_tx) 537, since the pilot power gain is relative tothe total forward link transmit power (Ior_tx) 536. In anotherconfiguration, adjusting 612 the transmit power 535 may include onlyadjusting the forward link pilot transmit power (Ecp_tx) 537. Adjusting612 the transmit power 535 may include increasing and decreasing thetransmit power 535.

In one configuration, the femto access point 419 may detect activehandoffs of a wireless communication device 420. Upon detecting anactive handoff (active handoffs are signaled via the core network), thefemto access point 419 may start a registration timer 528 and count thenumber of active handoffs (or active handoff attempts) by the wirelesscommunication device 420 during the registration time 529. If frequentactive handoffs are detected over the registration time 529, the femtoaccess point 419 may adjust 612 the transmit power 535.

The femto access point 419 may then determine 613 whether a change to anidle mode pilot trigger threshold on the wireless communication device420 is needed. The idle mode pilot trigger threshold is discussed inadditional detail below in relation to FIG. 12. The idle mode pilottrigger threshold may be an adjustable threshold used by the wirelesscommunication device 420 to determine when to search for pilot signalsfrom other base stations while in idle mode. The femto access point mayadjust 614 an idle mode pilot trigger threshold on the wirelesscommunication device 420 if a change to the idle mode pilot triggerthreshold is needed. If a change to the idle mode pilot triggerthreshold on the wireless communication device 420 is not needed, thefemto access point may return to waiting to receive 602 anotherregistration request from a wireless communication device 420.

Adjusting 614 the idle mode pilot trigger threshold on the wirelesscommunication device 420 may cause the wireless communication device 420to delay searches for other base stations, thereby causing the wirelesscommunication device 420 to stay on the femto access point 419 longer.Thus, frequent idle handoff effects are naturally reduced. Adjusting 614an idle mode pilot trigger threshold on the wireless communicationdevice 420 may include sending instructions to the wirelesscommunication device 420 that include changes to the idle mode pilottrigger threshold.

Adjusting 614 an idle mode pilot trigger threshold on the wirelesscommunication device 420 may be done proactively or upon detection offrequent idle handoffs based on registration attempts. The femto accesspoint 419 may only adjust 614 an idle mode pilot trigger threshold onthe wireless communication device 420 if such adjustable controls areavailable to the femto access point 419. Though such capability does notexist in current cdma2000 femto access points 419, this is likely to beavailable in the future. However, this solution readily applies to WCDMAsystems where separate thresholds are provided to triggerintra-frequency or inter-frequency pilot searches. The femto accesspoint 419 may then wait to receive 602 another registration request froma wireless communication device 420.

Femto access points such as cdma2000 1x femtocells can transmit beaconson frequencies different from the normal operating forward linkfrequency when the femtocell forward link frequency is different fromthe neighboring macro base station frequencies. In such a case, awireless communication device performs an idle hand-in from a macro basestation to a femtocell via a beacon, but performs inter-frequency idlehand-out directly from the femtocell to the macro base station withoutany beacons. Thus, to avoid frequent handoffs, the femtocell may adjustthe power level of beacon transmissions in conjunction with adjustingthe transmit power level of the normal operating forward link frequency.

The method 600 of FIG. 6 described above may be performed by varioushardware and/or software component(s) and/or module(s) corresponding tothe means-plus-function system 700 illustrated in FIG. 7. In otherwords, blocks 602 through 614 illustrated in FIG. 6 correspond tomeans-plus-function blocks 702 through 714 illustrated in FIG. 7. Forexample, system 700 can reside at least partially within a base station,or mobile device, etc. It is to be appreciated that system 700 isrepresented as including functional blocks, which can representfunctions implemented by a processor, software, or combination thereof,such as, for example, firmware. Additionally, the system 700 may includea memory (not shown) that retains instructions for executing functionsassociated with blocks 702 through 714.

FIG. 8 is another flow diagram of a method 800 for reducing frequenthandoffs. The method 800 may be performed by a femto access point 419.The femto access point 419 may receive 802 a registration request from awireless communication device 420. The wireless communication device 420may or may not be part of the closed subscriber group (CSG) associatedwith the femto access point 419. When a wireless communication device420 performs idle handoff from a macro base station 418 to a femtoaccess point 419, the wireless communication device 420 sends aregistration request to the femto access point 419. Upon receiving theregistration request, the femto access point 419 may start 804 aregistration timer 528.

The femto access point 419 may then count 806 the number 526 ofregistration requests received from the wireless communication device420 until the registration timer 528 expires 808. The femto access point419 may compare 810 the number 526 of registration requests receivedfrom the wireless communication device 420 with a registration threshold527. If the number 526 of registration requests received from thewireless communication device 420 is not greater than the registrationthreshold 527, the femto access point 419 may wait to receive 802another registration request from a wireless communication device 420.

If the number 526 of registration requests received from the wirelesscommunication device 420 is greater than the registration threshold 527,the femto access point 419 may determine 812 that the wirelesscommunication device 420 is performing frequent idle handoffs. As anexample, the registration time 529 can be set to two minutes and theregistration threshold 527 can be set to five. If more than fiveregistration attempts from the wireless communication device 420 aredetected during the two minute registration timer 529, the femto accesspoint 419 may determine 812 that the wireless communication device 420is performing frequent idle handoffs. As another example, theregistration time 529 can be set to two hours and the registrationthreshold 527 can be set to fifty. If more than fifty registrationattempts from the wireless communication device 420 are detected duringthe two hour registration timer 529, the femto access point 419 maydetermine 812 that the wireless communication device 420 is performingfrequent idle handoffs. Overall, the registration timer 528 and theregistration threshold 527 can be configured and optimized to reducefrequent handoffs.

The femto access point 419 may then determine 814 whether the wirelesscommunication device 420 is part of a closed subscriber group (CSG)associated with the femto access point 419. If the wirelesscommunication device 420 is part of a closed subscriber group (CSG)associated with the femto access point 419, it may be desirable to makethe wireless communication device 420 stick to the femto access point419. In other words, it may be desirable that the wireless communicationdevice 420 communicate with the femto access point 419 for as long aspossible. The femto access point 419 may thus increase 818 the transmitpower 535 to improve forward link coverage and thereby prevent frequenthandoffs of a wireless communication device 420 that is part of a closedsubscriber group (CSG) associated with the femto access point 419. Inone configuration, the femto access point 419 may increase 818 thetransmit power 535 by a power adjustment factor 532. Power adjustmentfactors 532 are discussed in further detail below in relation to FIG.10. In one configuration, the femto access point 419 may increase 818the transmit power 535 on the forward link pilot channel Walsh code by afew dBs.

In one configuration, the femto access point 419 may proactively chooseto adjust the transmit power 535 to adjust the coverage area of thefemto access point 419. This technique is especially useful when femtoaccess points 419 have a dedicated frequency different from neighboringmacro base stations 418 because a higher pilot and overhead power willnot cause interference to the macro network, but will provide good femtoaccess point 419 coverage to delay idle handoffs.

Depending on the available transmit power 535 headroom, the femto accesspoint 419 may increase the total forward link transmit power (Ior_tx)536 (which also increases the forward link pilot transmit power (Ecp_tx)537, since pilot power gain is relative to the total transmit power) oronly the forward link pilot transmit power (Ecp_tx) 537 by adjusting thepilot channel gain. Increasing either the total forward link transmitpower (Ior_tx) 536 or only the forward link pilot transmit power(Ecp_tx) 537 may cause signals received by the wireless communicationdevice 420 from a macro base station 418 to be weaker than signalsreceived by the wireless communication device 420 from the femto accesspoint 419. This may reduce the idle handoffs of the wirelesscommunication device 420. The femto access point 419 may then wait toreceive 802 another registration request from a wireless communicationdevice 420.

If the wireless communication device 420 is not part of a closedsubscriber group (CSG) associated with the femto access point 419, itmay be desirable to force the wireless communication device 420 out ofthe coverage area of the femto access point 419. The femto access point419 may thus reduce 816 the transmit power 535. The femto access point419 may reduce the total forward link transmit power (Ior_tx) 536 oronly the forward link pilot transmit power (Ecp_tx) 537 to force thewireless communication device 420 out of the coverage area of the femtoaccess point 419. In one configuration, the femto access point 419 mayreduce 816 the transmit power 535 by a power adjustment factor 532.Power adjustment factors 532 are discussed in further detail below inrelation to FIG. 10. The femto access point 532 may then wait to receive802 another registration request from a wireless communication device420.

The method 800 of FIG. 8 described above may be performed by varioushardware and/or software component(s) and/or module(s) corresponding tothe means-plus-function system 900 illustrated in FIG. 9. In otherwords, blocks 802 through 818 illustrated in FIG. 8 correspond tomeans-plus-function blocks 902 through 918 illustrated in FIG. 9. Forexample, system 900 can reside at least partially within a base station,or mobile device, etc. It is to be appreciated that system 900 isrepresented as including functional blocks, which can representfunctions implemented by a processor, software, or combination thereof,such as, for example, firmware. Additionally, the system 900 may includea memory (not shown) that retains instructions for executing functionsassociated with blocks 902 through 918.

FIG. 10 is a flow diagram of yet another method 1000 for reducingfrequent handoffs. The method 100 may be performed by a femto accesspoint 419. The femto access point 419 may detect 1002 frequent idlehandoffs by a wireless communication device 420. In one configuration,the femto access point 419 may detect 1002 frequent idle handoffs by awireless communication device 420 by counting the number 526 ofregistration attempts made by the wireless communication device 420. Thefemto access point 419 may then adjust 1004 the transmit power 535 ofthe femto access point 419 by a power adjustment factor 532. Asdiscussed above in relation to FIG. 5, the femto access point 419 mayincrease or decrease either the total forward link transmit power(Ior_tx) 536 or only the forward link pilot transmit power (Ecp_tx) 537.Power is increased if wireless communication devices 420 that are partof the closed subscriber group (CSG) associated with the femto accesspoint 419 are performing frequent idle handoffs, thereby improving theforward link coverage area of the femto access point 419. Power isdecreased if wireless communication devices 420 that are not part of theclosed subscriber group (CSG) associated with the femto access point 419are performing frequent idle handoffs, thereby shrinking the forwardlink coverage area of the femto access point 419.

Power adjustments are only done for a certain duration (e.g., tenminutes) so as to not affect normal coverage by the femto access point419. Thus, the femto access point 419 may start 1006 a power adjustmenttimer 533 after adjusting 1004 the transmit power of the femto accesspoint 419 by the power adjustment factor 532. Once the power adjustmenttimer 533 has expired 1008, the femto access point 419 may determine1012 whether frequent idle handoffs by the wireless communication device420 were detected while the power adjustment timer 533 was running Iffrequent idle handoffs by the wireless communication device 420 weredetected while the power adjustment timer 533 was running, the femtoaccess point 419 may incrementally increase 1014 the power adjustmenttime 534 (i.e., from ten minutes to fifteen minutes, then twentyminutes) used by the power adjustment timer 533. The femto access point419 may also incrementally increase 1016 the power adjustment factor532.

For example, if a wireless communication device 420 that is part of theclosed subscriber group (CSG) associated with the femto access point 419is performing frequent handoffs and power was increased earlier by poweradjustment factor=X dB prior to the power adjustment timer 533expiration, then the power adjustment factor is made (X+1) dB and ineffect the total transmit power is increased further by 1 dB. If awireless communication device 420 that is not part of the closedsubscriber group (CSG) associated with the femto access point 419 isperforming frequent handoffs and power was decreased earlier by poweradjustment factor=X dB prior to the power adjustment timer 533expiration, then the power adjustment factor is made (X+1) dB and so thetotal transmit power is reduced further by 1 dB

Thus, the transmit power adjustment factor 532 and the duration forwhich transmit power 535 is adjusted may be adapted based on theseverity of frequent handoff events. The femto access point 419 may thenagain adjust 1004 the transmit power 535 of the femto access point 419by the power adjustment factor 532.

If frequent idle handoffs by the wireless communication device 420 werenot detected while the power adjustment timer 533 was running, the femtoaccess point 419 may incrementally decrease 1018 the power adjustmenttime 534 used by the power adjustment timer 533. The femto access point419 may also incrementally decrease 1020 the power adjustment factor532.

For example, a wireless communication 420 that is part of the closedsubscriber group (CSG) associated with the femto access point 419 wasperforming frequent idle handoffs and power was increased earlier bypower adjustment factor=X dB prior to the power adjustment timer 533expiration. If this wireless communication device 420 does not performfrequent idle handoffs when the power adjustment timer 533 is runningthen the power adjustment factor is made (X−1) dB and so the new totaltransmit power is reduced by 1 dB.

The femto access point 419 may readjust 1022 the transmit power to theprevious transmit power level. The femto access point 419 may then waitto detect 1002 frequent idle handoffs by a wireless communication device420.

The method 1000 of FIG. 10 described above may be performed by varioushardware and/or software component(s) and/or module(s) corresponding tothe means-plus-function system 1100 illustrated in FIG. 11. In otherwords, blocks 1002 through 1022 illustrated in FIG. 10 correspond tomeans-plus-function blocks 1102 through 1122 illustrated in FIG. 11. Forexample, system 1100 can reside at least partially within a basestation, or mobile device, etc. It is to be appreciated that system 1100is represented as including functional blocks, which can representfunctions implemented by a processor, software, or combination thereof,such as, for example, firmware. Additionally, the system 1100 mayinclude a memory (not shown) that retains instructions for executingfunctions associated with blocks 1102 through 1122.

In one configuration, the femto access point 419 can adjust the transmitpower 535 according to the time of the day. For example, a femto accesspoint 419 can learn that preferred users (i.e., wireless communicationdevices 420 that are part of the closed subscriber group (CSG)associated with the femto access point 419) are out of the home duringregular business hours, allowing the femto access point 419 to reducethe transmit power 535 to limit handoffs/registrations by non-preferredusers during regular business hours.

FIG. 12 is a block diagram illustrating a handoff determination module1421. The handoff determination module 1421 of FIG. 12 may be oneconfiguration of the handoff determination modules 421 a-b of FIG. 4.The handoff determination module 1421 may be located on a wirelesscommunication device 420 (i.e., the first wireless communication device420 or the second wireless communication device 420).

The handoff determination module 1421 may include an observationthreshold 1450. The observation threshold 1450 may be a predefinedthreshold that is used by the handoff determination module 1421 todetermine when to delay idle handoffs. The handoff determination module1421 may also include an observation timer 1451 with an observation time1452.

The handoff determination module 1421 may include a registrationattempts counter 1453 that counts the number 1454 of registrationattempts/requests by the wireless communication device 420 to a femtoaccess point 419. If the number 1454 of registrations attempted by awireless communication device 420 during the observation time 1452 isgreater than the observation threshold 1450, the handoff determinationmodule 1421 may delay idle handoffs away from the femto access point 419(i.e., idle handout) for a handout time 1457 using a handout timer 1456.In one configuration, the handout time 1457 may be between two and fiveminutes. This mechanism is discussed in further detail below in relationto FIG. 13.

The handoff determination module 1421 may include a handout threshold1455. The handout threshold 1455 may be a predefined threshold that isused by the handoff determination module 1421 to determine when tohandoff from the femto access point 419. For example, the handoutthreshold 1455 may be set to −15 dB or another appropriate value atwhich the wireless communication device 420 can still receive servicefrom the femto access point 419 with reasonably good quality. Unless thepower level of signals received from the femto access point 419 fallsbelow the handout threshold 1455 during the handout time 1457, thehandoff determination module 1421 may prevent the wireless communicationdevice 420 from performing an idle handoff away from the femto accesspoint 419.

The handoff determination module 1421 may include an idle mode pilotsearch trigger threshold 1430. Idle mode pilot search trigger thresholds1430 were discussed above in relation to FIG. 6. An idle mode pilotsearch trigger threshold 1430 may determine the amount of time awireless communication device 420 waits before searching for pilotsignals from other base stations. In one configuration, the idle modepilot search trigger threshold 1430 may reflect a minimum increase inreceived pilot power from a non-serving base station over the receivedpilot power from a current serving base station before an idle handoffis triggered to leave the current serving base station and handoff tothe non-serving base station.

The wireless communication device 420 may receive instructions from afemto access point 419 to adjust the idle mode pilot search triggerthreshold 1430. In one configuration, the instructions to adjust theidle mode pilot search trigger threshold 1430 may include the specificadjustments to be made to the idle mode pilot search trigger threshold1430. The wireless communication device 420 may determine whetherchanges are needed to the idle mode pilot search trigger threshold 1430.In one configuration, determining whether changes are needed to the idlemode pilot search trigger threshold 1430 may include determining whetherinstructions to adjust the idle mode pilot search trigger threshold 1430were received from a femto access point 419.

FIG. 13 is a flow diagram of a method 1500 for reducing handoffs by awireless communication device 420. The method 1500 may be performed bythe wireless communication device 420. The wireless communication device420 may or may not be part of a closed subscriber group (CSG) associatedwith a femto access point 419. The wireless communication device 420 maybe able to distinguish between femto access point 419 pilot and macrobase station 418 pilot signatures (PNs).

The wireless communication device 420 may send 1502 a registrationrequest to the femto access point 419. In one configuration, sending1502 a registration request to the femto access point 419 may be part ofperforming registration to the femto access point 419. If the wirelesscommunication device 420 is not part of the closed subscriber group(CSG) associated with the femto access point 419, the registration tothe femto access point 419 may fail. Alternatively, the wirelesscommunication device 420 may be granted limited access to the femtoaccess point 419.

The wireless communication device 420 may start 1504 an observationtimer 1451. The wireless communication device 420 may then count 1506the number 1454 of registrations attempts to the femto access point 419.The number 1454 of registration attempts to the femto access point 419may include both successful registrations and failed registrationattempts. The observation timer 1451 may expire 1508 after theobservation time 1452 has elapsed. The wireless communication device 420may then detect 1510 a trigger for an idle handoff away from the femtoaccess point 419. The wireless communication device 420 may determine1512 whether the number 1454 of registrations attempted to the femtoaccess point 419 is greater than an observation threshold 1450.

If the number 1454 of registrations performed to the femto access point419 is greater than the observation threshold 1450, the wirelesscommunication device 420 has detected a frequent handoff condition. Thewireless communication device 420 may start 1516 a handout timer 1456.The wireless communication device 420 may then determine 1518 whetherthe forward link pilot received power (Ecp/Io) from the femto accesspoint 419 is above a handout threshold 1455.

If the forward link pilot received power (Ecp/Io) from the femto accesspoint 419 is above the handout threshold 1455, the wirelesscommunication device 420 may determine 1520 whether the handout timer1456 has expired. If the handout timer 1456 has not expired, thewireless communication device 420 may return to determining 1518 if theforward link pilot received power (Ecp/Io) from the femto access point419 is above the handout threshold 1455.

If the handout timer 1456 has expired, the wireless communication device420 may determine 1522 whether the handout trigger condition wassatisfied within a monitoring period. In other words, the wirelesscommunication device 420 may determine whether the conditions thattriggered the idle handoff away from the femto access point 419 stillindicate that an idle handoff away from the femto access point 419 isnecessary. If the handout trigger condition was satisfied within amonitoring period, the wireless communication device 420 may perform1514 the idle handoff away from the femto access point 419. If thehandout trigger condition was not satisfied within a monitoring period,the wireless communication device 420 may stay 1524 on the femto accesspoint 419.

If the forward link pilot received power (Ecp/Io) from the femto accesspoint 419 falls below the handout threshold 1455, the wirelesscommunication device 420 may perform 1514 the idle handoff away from thefemto access point 419 without further delay. If the number 1454 ofregistrations attempted by the wireless communication device 420 to thefemto access point 419 is not greater than the observation threshold1450, the wireless communication device 420 may perform 1514 the idlehandoff away from the femto access point 419 without any delay.

The method 1500 of FIG. 13 described above may be performed by varioushardware and/or software component(s) and/or module(s) corresponding tothe means-plus-function system 1600 illustrated in FIG. 14. In otherwords, blocks 1502 through 1524 illustrated in FIG. 13 correspond tomeans-plus-function blocks 1602 through 1624 illustrated in FIG. 14. Forexample, system 1600 can reside at least partially within a basestation, or mobile device, etc. It is to be appreciated that system 1600is represented as including functional blocks, which can representfunctions implemented by a processor, software, or combination thereof,such as, for example, firmware. Additionally, the system 1600 mayinclude a memory (not shown) that retains instructions for executingfunctions associated with blocks 1602 through 1624.

FIG. 17 is a flow diagram of another method 1700 for reducing frequenthandoffs by a wireless communication device 420. The method 1700 may beperformed by the wireless communication device 420. The wirelesscommunication device 420 may or may not be part of a closed subscribergroup (CSG) associated with a femto access point 419.

The wireless communication device 420 may send 1702 a registrationrequest to the femto access point 419. In one configuration, sending1702 a registration request to the femto access point 419 may be part ofperforming registration to the femto access point 419. The wirelesscommunication device 420 may detect 1704 a trigger for an idle handoffaway from the femto access point 419. The wireless communication device420 may then start 1706 a handout timer 1456. The wireless communicationdevice 420 may determine 1708 whether the forward link pilot receivedpower (Ecp/Io) from the femto access point 419 is below a handoutthreshold 1455. As an example, the handout threshold 1455 may be areceived power of −15 dB (below which overhead channels may not bedecoded successfully).

If the forward link pilot received power (Ecp/Io) from the femto accesspoint 419 is below the handout threshold 1455, the wirelesscommunication device 420 may perform 1710 an idle handoff away from thefemto access point 419. If the forward link pilot received power(Ecp/Io) from the femto access point 419 is not below the handoutthreshold 1455, the wireless communication device 420 may determine 1712whether the handout timer 1456 has expired. If the handout timer 1456has not expired, the wireless communication device may return todetecting 1704 a trigger for an idle handoff away from the femto accesspoint 419.

If the handout timer 1456 has expired, the wireless communication device420 may determine 1714 whether the handout trigger condition wassatisfied within a monitoring period. In other words, the wirelesscommunication device 420 may determine whether conditions are such thatan idle handoff away from the femto access point 419 is still necessary(i.e., triggered). If the handout condition is satisfied within amonitoring period, the wireless communication device 420 may stay 1716on the femto access point 419. If the handout condition is not satisfiedwithin a monitoring period, the wireless communication device 420 mayperform 1710 an idle handoff away from the femto access point 419. Thus,the method 1700 simply delays idle handoffs based on the handout timer1456, irrespective of whether frequent handoffs are occurring.

The method 1700 of FIG. 15 described above may be performed by varioushardware and/or software component(s) and/or module(s) corresponding tothe means-plus-function system 1800 illustrated in FIG. 16. In otherwords, blocks 1702 through 1716 illustrated in FIG. 15 correspond tomeans-plus-function blocks 1802 through 1816 illustrated in FIG. 16. Forexample, system 1800 can reside at least partially within a basestation, or mobile device, etc. It is to be appreciated that system 1800is represented as including functional blocks, which can representfunctions implemented by a processor, software, or combination thereof,such as, for example, firmware. Additionally, the system 1800 mayinclude a memory (not shown) that retains instructions for executingfunctions associated with blocks 1802 through 1816.

FIG. 17 illustrates two wireless devices in a multiple-in andmultiple-out (MIMO) system 1900. A MIMO system 1900 employs multiple(N_(T)) transmit antennas 1924 and multiple (N_(R)) receive antennas1952 for data transmission. A MIMO channel formed by the N_(T) transmitand N_(R) receive antennas may be decomposed into N_(S) independentchannels, which are also referred to as spatial channels, whereN_(S)<min{N_(T), N_(R)}. Each of the N_(S) independent channelscorresponds to a dimension. The MIMO system may provide improvedperformance (e.g., higher throughput and/or greater reliability) if theadditional dimensionalities created by the multiple transmit and receiveantennas are utilized.

A MIMO system 1900 may support time division duplex (“TDD”) andfrequency division duplex (“FDD”). In a TDD system, the forward andreverse link transmissions are on the same frequency region so that thereciprocity principle allows the estimation of the forward link channelfrom the reverse link channel. This enables a transmitting wirelessdevice 1910 to extract transmit beamforming gain on the forward linkwhen multiple antennas are available at the receiving wireless device1950.

The teachings herein may be incorporated into a node (e.g., a device)employing various components for communicating with at least one othernode. At the transmitting device 1910, traffic data for a number of datastreams is provided from a data source 1912 to a transmit (“TX”) dataprocessor 1914.

In some aspects, each data stream is transmitted over a respectivetransmit antenna. The TX data processor 1914 formats, codes andinterleaves the traffic data for each data stream based on a particularcoding scheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot datausing OFDM techniques. The pilot data is typically a known data patternthat is processed in a known manner and may be used at the receiversystem to estimate the channel response. The multiplexed pilot and codeddata for each data stream is then modulated (i.e., symbol mapped) basedon a particular modulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM)selected for that data stream to provide modulation symbols. The datarate, coding and modulation for each data stream may be determined byinstructions performed by a processor 1930. A data memory 1932 may storeprogram code, data and other information used by the processor 1930 orother components of the device 1910.

The modulation symbols for all data streams are then provided to a TXMIMO processor 1920, which may further process the modulation symbols(e.g., for OFDM). The TX MIMO processor 1920 then provides N_(T)modulation symbol streams to N_(T) transceivers (“XCVR”) 1922A through1922T. In some aspects, the TX MIMO processor 1920 applies beamformingweights to the symbols of the data streams and to the antenna from whichthe symbol is being transmitted.

Each transceiver 1922 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transceivers 1922A through 1922T are thentransmitted from N_(T) antennas 1924A through 1924T, respectively.

At the receiving wireless device 1950, the transmitted modulated signalsare received by N_(R) antennas 1952A through 1952R and the receivedsignal from each antenna 1952 is provided to a respective transceiver(“XCVR”) 1954A through 1954R. Each transceiver 1954 conditions (e.g.,filters, amplifies and downconverts) a respective received signal,digitizes the conditioned signal to provide samples and furtherprocesses the samples to provide a corresponding “received” symbolstream.

A receive (“RX”) data processor 1960 then receives and processes theN_(R) received symbol streams from N_(R) transceivers 1954 based on aparticular receiver processing technique to provide N_(T) “detected”symbol streams. The RX data processor 1960 then demodulates,deinterleaves and decodes each detected symbol stream to recover thetraffic data for the data stream. The processing by the RX dataprocessor 1960 is complementary to that performed by the TX MIMOprocessor 1920 and the TX data processor 1914 at the transmittingwireless device 1910.

A processor 1970 periodically determines which pre-coding matrix to use(discussed below). The processor 1970 formulates a reverse link messagecomprising a matrix index portion and a rank value portion. A datamemory 1972 may store program code, data and other information used bythe processor 1970 or other components of the device 1950.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 1938,which also receives traffic data for a number of data streams from adata source 1936, modulated by a modulator 1980, conditioned by thetransceivers 1954A through 1954R and transmitted back to the device1910.

At the device 1910, the modulated signals from the device 1950 arereceived by the antennas 1924, conditioned by the transceivers 1922,demodulated by a demodulator (“DEMOD”) 1940 and processed by a RX dataprocessor 1942 to extract the reverse link message transmitted by thedevice 1950. The processor 1930 then determines which pre-coding matrixto use for determining the beam-forming weights then processes theextracted message.

FIG. 18 illustrates certain components that may be included within afemto access point 2019. A femto access point 2019 may also be referredto as, and may include some or all of the functionality of, a femtocell,a picocell, a home NodeB (HNB), a home evolved NodeB (HeNB), etc. Thefemto access point 2019 includes a processor 2003. The processor 2003may be a general purpose single- or multi-chip microprocessor (e.g., anARM), a special purpose microprocessor (e.g., a digital signal processor(DSP)), a microcontroller, a programmable gate array, etc. The processor2003 may be referred to as a central processing unit (CPU). Althoughjust a single processor 2003 is shown in the femto access point 2019 ofFIG. 18, in an alternative configuration, a combination of processors(e.g., an ARM and DSP) could be used.

The femto access point 2019 also includes memory 2005. The memory 2005may be any electronic component capable of storing electronicinformation. The memory 2005 may be embodied as random access memory(RAM), read-only memory (ROM), magnetic disk storage media, opticalstorage media, flash memory devices in RAM, on-board memory includedwith the processor, EPROM memory, EEPROM memory, registers, and soforth, including combinations thereof.

Data 2007 and instructions 2009 may be stored in the memory 2005. Theinstructions 2009 may be executable by the processor 2003 to implementthe methods disclosed herein. Executing the instructions 2009 mayinvolve the use of the data 2007 that is stored in the memory 2005. Whenthe processor 2003 executes the instructions 2009, various portions ofthe instructions 2009 a may be loaded onto the processor 2003, andvarious pieces of data 2007 a may be loaded onto the processor 2003.

The femto access point 2019 may also include a transmitter 2011 and areceiver 2013 to allow transmission and reception of signals to and fromthe femto access point 2019. The transmitter 2011 and receiver 2013 maybe collectively referred to as a transceiver 2015. An antenna 2017 maybe electrically coupled to the transceiver 2015. The femto access point2019 may also include (not shown) multiple transmitters, multiplereceivers, multiple transceivers and/or additional antennas.

The various components of the femto access point 2019 may be coupledtogether by one or more buses, which may include a power bus, a controlsignal bus, a status signal bus, a data bus, etc. For the sake ofclarity, the various buses are illustrated in FIG. 18 as a bus system2021.

FIG. 19 illustrates certain components that may be included within awireless communication device 2120. The wireless communication device2120 may be an access terminal, a mobile station, a user equipment (UE),etc. The wireless communication device 2120 includes a processor 2103.The processor 2103 may be a general purpose single- or multi-chipmicroprocessor (e.g., an ARM), a special purpose microprocessor (e.g., adigital signal processor (DSP)), a microcontroller, a programmable gatearray, etc. The processor 2103 may be referred to as a centralprocessing unit (CPU). Although just a single processor 2103 is shown inthe wireless communication device 2120 of FIG. 19, in an alternativeconfiguration, a combination of processors (e.g., an ARM and DSP) couldbe used.

The wireless communication device 2120 also includes memory 2105. Thememory 2105 may be any electronic component capable of storingelectronic information. The memory 2105 may be embodied as random accessmemory (RAM), read-only memory (ROM), magnetic disk storage media,optical storage media, flash memory devices in RAM, on-board memoryincluded with the processor, EPROM memory, EEPROM memory, registers, andso forth, including combinations thereof.

Data 2107 and instructions 2109 may be stored in the memory 2105. Theinstructions 2109 may be executable by the processor 2103 to implementthe methods disclosed herein. Executing the instructions 2109 mayinvolve the use of the data 2107 that is stored in the memory 2105. Whenthe processor 2103 executes the instructions 2109, various portions ofthe instructions 2109 a may be loaded onto the processor 2103, andvarious pieces of data 2107 a may be loaded onto the processor 2103.

The wireless communication device 2120 may also include a transmitter2111 and a receiver 2113 to allow transmission and reception of signalsto and from the wireless communication device 2106. The transmitter 2111and receiver 2113 may be collectively referred to as a transceiver 2115.An antenna 2117 may be electrically coupled to the transceiver 2115. Thewireless communication device 2120 may also include (not shown) multipletransmitters, multiple receivers, multiple transceivers and/oradditional antennas.

The various components of the wireless communication device 2120 may becoupled together by one or more buses, which may include a power bus, acontrol signal bus, a status signal bus, a data bus, etc. For the sakeof clarity, the various buses are illustrated in FIG. 19 as a bus system2121.

The techniques described herein may be used for various communicationsystems, including communication systems that are based on an orthogonalmultiplexing scheme. Examples of such communication systems includeOrthogonal Frequency Division Multiple Access (OFDMA) systems,Single-Carrier Frequency Division Multiple Access (SC-FDMA) systems, andso forth. An OFDMA system utilizes orthogonal frequency divisionmultiplexing (OFDM), which is a modulation technique that partitions theoverall system bandwidth into multiple orthogonal sub-carriers. Thesesub-carriers may also be called tones, bins, etc. With OFDM, eachsub-carrier may be independently modulated with data. An SC-FDMA systemmay utilize interleaved FDMA (IFDMA) to transmit on sub-carriers thatare distributed across the system bandwidth, localized FDMA (LFDMA) totransmit on a block of adjacent sub-carriers, or enhanced FDMA (EFDMA)to transmit on multiple blocks of adjacent sub-carriers. In general,modulation symbols are sent in the frequency domain with OFDM and in thetime domain with SC-FDMA.

The term “determining” encompasses a wide variety of actions and,therefore, “determining” can include calculating, computing, processing,deriving, investigating, looking up (e.g., looking up in a table, adatabase or another data structure), ascertaining and the like. Also,“determining” can include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” can include resolving, selecting, choosing, establishingand the like.

The phrase “based on” does not mean “based only on,” unless expresslyspecified otherwise. In other words, the phrase “based on” describesboth “based only on” and “based at least on.”

The term “processor” should be interpreted broadly to encompass ageneral purpose processor, a central processing unit (CPU), amicroprocessor, a digital signal processor (DSP), a controller, amicrocontroller, a state machine, and so forth. Under somecircumstances, a “processor” may refer to an application specificintegrated circuit (ASIC), a programmable logic device (PLD), a fieldprogrammable gate array (FPGA), etc. The term “processor” may refer to acombination of processing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The term “memory” should be interpreted broadly to encompass anyelectronic component capable of storing electronic information. The termmemory may refer to various types of processor-readable media such asrandom access memory (RAM), read-only memory (ROM), non-volatile randomaccess memory (NVRAM), programmable read-only memory (PROM), erasableprogrammable read-only memory (EPROM), electrically erasable PROM(EEPROM), flash memory, magnetic or optical data storage, registers,etc. Memory is said to be in electronic communication with a processorif the processor can read information from and/or write information tothe memory. Memory that is integral to a processor is in electroniccommunication with the processor.

The terms “instructions” and “code” should be interpreted broadly toinclude any type of computer-readable statement(s). For example, theterms “instructions” and “code” may refer to one or more programs,routines, sub-routines, functions, procedures, etc. “Instructions” and“code” may comprise a single computer-readable statement or manycomputer-readable statements.

The functions described herein may be implemented in software orfirmware being executed by hardware. The functions may be stored as oneor more instructions on a computer-readable medium. The terms“computer-readable medium” or “computer-program product” refers to anytangible storage medium that can be accessed by a computer or aprocessor. By way of example, and not limitation, a computer-readablemedium may comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Disk and disc, as used herein, includes compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray® disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isrequired for proper operation of the method that is being described, theorder and/or use of specific steps and/or actions may be modifiedwithout departing from the scope of the claims.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein, suchas those illustrated by FIGS. 6, 8, 10, 13 and 15, can be downloadedand/or otherwise obtained by a device. For example, a device may becoupled to a server to facilitate the transfer of means for performingthe methods described herein. Alternatively, various methods describedherein can be provided via a storage means (e.g., random access memory(RAM), read-only memory (ROM), a physical storage medium such as acompact disc (CD) or floppy disk, etc.), such that a device may obtainthe various methods upon coupling or providing the storage means to thedevice.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the systems, methods, and apparatus described herein withoutdeparting from the scope of the claims.

What is claimed is:
 1. A method for reducing frequent idle handoffs of awireless communication device, comprising: sending a registrationrequest to a femto access point; detecting a trigger for an idle handoffaway from the femto access point; starting a handout timer; anddetermining whether a handout trigger condition is satisfied within amonitoring period after the handout timer has expired.
 2. The method ofclaim 1, wherein the trigger for an idle handoff away from the femtoaccess point is an idle handout trigger.
 3. The method of claim 1,further comprising performing an idle handoff away from the femto accesspoint if the handout trigger condition is satisfied within a monitoringperiod after the handout timer has expired.
 4. The method of claim 1,further comprising staying on the femto access point if the handouttrigger condition is not satisfied within a monitoring period after thehandout timer has expired.
 5. The method of claim 1, further comprisingcomparing a forward link received power from the femto access point witha handout threshold before the handout timer has expired, wherein theidle handoff away from the femto access point is performed prior to thehandout timer expiring if the forward link received power from the femtoaccess point is less than the handout threshold.
 6. The method of claim1, further comprising: starting an observation timer; counting a numberof registrations attempted to the femto access point before theobservation timer has expired; and performing an idle handoff away fromthe femto access point after the observation timer has expired if thenumber of registrations attempted to the femto access point is greaterthan an observation threshold and handoff away from the femto accesspoint is triggered.
 7. The method of claim 1, wherein the wirelesscommunication device is part of a closed subscriber group (CSG)associated with the femto access point.
 8. The method of claim 1,wherein the wireless communication device is not part of a closedsubscriber group (CSG) associated with the femto access point.
 9. Themethod of claim 1, wherein the trigger for an idle handoff away from thefemto access point is to a macro base station.
 10. The method of claim1, wherein the wireless communication device is able to distinguishbetween pilots received from the femto access point and pilots receivedfrom a macro base station.
 11. A wireless device configured for reducingfrequent idle handoffs of the wireless device, comprising: a processor;memory in electronic communication with the processor; instructionsstored in the memory, the instructions being executable by the processorto: send a registration request to a femto access point; detect atrigger for an idle handoff away from the femto access point; start ahandout timer; and determine whether a handout trigger condition issatisfied within a monitoring period after the handout timer hasexpired.
 12. The wireless device of claim 11, wherein the trigger for anidle handoff away from the femto access point is an idle handouttrigger.
 13. The wireless device of claim 11, wherein the instructionsare further executable by the processor to perform an idle handoff awayfrom the femto access point if the handout trigger condition issatisfied within a monitoring period after the handout timer hasexpired.
 14. The wireless device of claim 11, wherein the instructionsare further executable by the processor to stay on the femto accesspoint if the handout trigger condition is not satisfied within amonitoring period after the handout timer has expired.
 15. The wirelessdevice of claim 11, wherein the instructions are further executable tocompare a forward link received power from the femto access point with ahandout threshold before the handout timer has expired, wherein the idlehandoff away from the femto access point is performed prior to thehandout timer expiring if the forward link received power from the femtoaccess point is less than the handout threshold.
 16. The wireless deviceof claim 11, wherein the instructions are further executable to: startan observation timer; count a number of registrations attempted to thefemto access point before the observation timer has expired; and performan idle handoff away from the femto access point after the observationtimer has expired if the number of registrations attempted to the femtoaccess point is greater than an observation threshold and handoff awayfrom the femto access point is triggered.
 17. The wireless device ofclaim 11, wherein the wireless communication device is part of a closedsubscriber group (CSG) associated with the femto access point.
 18. Thewireless device of claim 11, wherein the wireless communication deviceis not part of a closed subscriber group (CSG) associated with the femtoaccess point.
 19. The wireless device of claim 11, wherein the triggerfor an idle handoff away from the femto access point is to a macro basestation.
 20. The wireless device of claim 11, wherein the wirelesscommunication device is able to distinguish between pilots received fromthe femto access point and pilots received from a macro base station.21. A wireless device configured for reducing frequent idle handoffs ofthe wireless device, comprising: means for sending a registrationrequest to a femto access point; means for detecting a trigger for anidle handoff away from the femto access point; means for starting ahandout timer; and means for determining whether a handout triggercondition is satisfied within a monitoring period after the handouttimer has expired.
 22. The wireless device of claim 21, furthercomprising means for performing an idle handoff away from the femtoaccess point if the handout trigger condition is satisfied within amonitoring period after the handout timer has expired.
 23. The wirelessdevice of claim 21, further comprising means for staying on the femtoaccess point if the handout trigger condition is not satisfied within amonitoring period after the handout timer has expired.
 24. The wirelessdevice of claim 21, further comprising means for comparing a forwardlink received power from the femto access point with a handout thresholdbefore the handout timer has expired, wherein the idle handoff away fromthe femto access point is performed prior to the handout timer expiringif the forward link received power from the femto access point is lessthan the handout threshold.
 25. The wireless device of claim 21, furthercomprising: means for starting an observation timer; means for countinga number of registration attempts to the femto access point before theobservation timer has expired; and means for performing the idle handoffaway from the femto access point before the observation timer hasexpired if the number of registration attempts to the femto access pointis greater than an observation threshold and handoff away from the femtoaccess point is triggered.
 26. A computer-program product for reducingfrequent idle handoffs of a wireless communication device, thecomputer-program product comprising a computer-readable medium havinginstructions thereon, the instructions comprising: code for causing atleast one computer to send a registration request to a femto accesspoint; code for causing at least one computer to detect a trigger for anidle handoff away from the femto access point; code for causing at leastone computer to start a handout timer; and code for determining whethera handout trigger condition is satisfied within a monitoring periodafter the handout timer has expired.
 27. The computer-program product ofclaim 26, wherein the instructions further comprise code for causing atleast one computer to perform an idle handoff away from the femto accesspoint if the handout trigger condition is satisfied within a monitoringperiod after the handout timer has expired.
 28. The computer-programproduct of claim 26, wherein the instructions further comprise code forcausing at least one computer to stay on the femto access point if thehandout trigger condition is not satisfied within a monitoring periodafter the handout timer has expired.
 29. The computer-program product ofclaim 26, wherein the instructions further comprise code for causing atleast one computer to compare a forward link received power from thefemto access point with a handout threshold before the handout timer hasexpired, wherein the idle handoff away from the femto access point isperformed prior to the handout timer expiring if the forward linkreceived power from the femto access point is less than the handoutthreshold.
 30. The computer-program product of claim 26, wherein theinstructions further comprise: code for causing at least one computer tostart an observation timer; code for causing at least one computer tocount a number of registration attempts to the femto access point beforethe observation timer has expired; and code for causing at least onecomputer to perform the idle handoff away from the femto access pointafter the observation timer has expired if the number of registrationattempts to the femto access point is greater than an observationthreshold and idle handoff away from the femto access point istriggered.